diff --git a/Source/MQTTnet/Client/MqttClient.cs b/Source/MQTTnet/Client/MqttClient.cs
index f84d277..e29e9d0 100644
--- a/Source/MQTTnet/Client/MqttClient.cs
+++ b/Source/MQTTnet/Client/MqttClient.cs
@@ -362,6 +362,7 @@ namespace MQTTnet.Client
 
                 while (!cancellationToken.IsCancellationRequested)
                 {
+                    // Values described here: [MQTT-3.1.2-24].
                     var keepAliveSendInterval = TimeSpan.FromSeconds(Options.KeepAlivePeriod.TotalSeconds * 0.75);
                     if (Options.KeepAliveSendInterval.HasValue)
                     {